The invention relates to a machine for the sterilisation of foodstuffs in cylindrical containers carried out at normal atmospheric pressure, in fact, a machine designed to maintain the sterilisation temperature of preserved foodstuffs for a predetermined length of time,--products such as tomato paste, cherries, apricots, peaches, apples, pears, fruit juices, pickles, jams and other such edibles prepared for retailing in cans, or cylindrical tubs or containers similar thereto,--and--subsequently, to to cool and dry the cans themselves, the entire operation carried out under conditions of normal atmospheric pressure.
Current techniques in the field consist of mechanised units comprising a chain-driven horizontal conveyor with drag members, this located immediately immediately above a like conveyor having gear-driven rollers; the cans, introduced between the two conveyors, are gathered and--simultaneously--caused to rotate in alternation so as to undergo a rapid, and uniform sterilisation by steam; other machines incorporate a chain-driven horizontal conveyor having blades by means of which the containers are moved along in ranks, the blades being mounted immediately above a surface laid out in the guise of a roller shutter,--or indeed smooth--, whose function is to provide alternating movement by means of an appropriate form of drive attached thereto, and impart the same to the cylindrical cans positioned therebetween in order to achieve a uniform sterilisation of the latter's contents by virtue of their rolling back and forth; yet another kind of machine is designed to sterilise cans arranged vertically, in rows, upon longitudinal stationary bars and like longitudinal movable bars, the latter inserted between the former and furnished with a capacity for alternating vertical movement, by means of which the cans are lifted, horizontal movement forward, by means of which the same are carried along, vertical movement by means of which the row of cans is brought to rest on the respective stationary bars, and horizontal movement by means of which to return to the original lifting position; the said longitudinal bars thus proceed by degrees, in a fashion known as "a passo di pellegrino," hereinafter referred to as "pilgrim step".
The techniques, such as they are, stand in need of further refinement with regard to the following: sterilising machines incorporating a chain-and-roller system are complex, and involve lengthy and costly maintenance operations; those machines which make use of a blade-and-alternating motion surface lead to poor handling of the product and, in the case of the roller-shutter type, to actual bursting of the cans, moreover, in the case of a smooth surface being adopted, the sliding away of cans owing to a distorted blade causes an inevitable shortfall in production due to inefficiency, this in addition to the elevated cost of plant, as the system calls for multi-level disposition of the cans; an effective homogenous penetration of the product in the can is not achieved by sterilising in the case of the third mentioned kind of machine, the pilgrim step machine. Besides the already listed drawbacks, the chain-and-roller, and the blade arrangements outlined in the first two kinds of machine present the further disadvantage that, in addition to their want of improvement functionally, they do not allow a diversity of shapes and sizes of product for sterilisation.
The above resume demonstrates a need for solution of those problems posed by a technique which will produce a simple sterilising operation, carried out by a machine arranged on one single level which, in addition to being inexpensive at the outset and requiring no special maintenance, effects the aforesaid operation uniformly and speedily as well as moving the cans and their contents briskly through the cycle.